Jennifer Brantley, a senior mechanical engineer with UltraCell in Livermore, Calif., on May 21, 2008., holds one of the fuel cell portable battery units that they manufacture. The fuel cell itself, at left, attaches to the entire unit to complete the design. Photo by Michael Macor/ San Francisco Chronicle

Photo: Michael Macor, The Chronicle

Jennifer Brantley, a senior mechanical engineer with UltraCell in...

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Jennifer Brantley, a senior mechanical engineer with UltraCell, in Livermore, Calif., on May 21, 2008., sketches out just how the chemical reactions work to produce electricity inside a fuel cell that they manufacture.Photo by Michael Macor/ San Francisco Chronicle

Napoleon Bonaparte once said that an army marches on its stomach. But were he alive today, the French general might put another item high on his list of logistical burdens - batteries.

Thanks to night vision goggles, battlefield computers and the pervasive radio, modern warriors can go into battle carrying up to 20 pounds of batteries, said Lt. Colonel Brian Maka, a Defense Department spokesman who served in the first Gulf War.

"When the soldier goes outside the wire and he is checking to make sure he has everything, batteries are right up there," Maka said in explaining the rationale behind a new federally sponsored contest called the Wearable Power Prize.

Pentagon officials hope to lighten soldiers' loads by encouraging the development of new technologies, such as fuel cells, that can provide more juice and weigh less than bulky batteries.

Rather than solicit bids, the Pentagon has set up a competition. In October, it will field test new power storage technologies in a contest offering three cash awards of $1 million, $500,000 and $250,000. The winning devices must deliver at least 96 hours worth of power in a package weighing less than 9 pounds.

More than 100 corporate, academic and private teams already have cleared the preliminary hurdles for this battery smackdown, according to John Hopkins, with the Army Research Lab in Adelphi, Md.

"We wanted to reach out beyond the traditional Department of Defense suppliers, and we believe that is happening," said Hopkins, who is helping coordinate the competition.

The Wearable Power Prize borrows a tactic employed with considerable success by the Defense Advanced Research Projects Agency. Hoping to hasten the development of robotic delivery trucks, the agency has held a series of competitions since 2004, offering cash prizes for the development of the sensors and software needed to steer a vehicle without a driver at the wheel.

Dozens of academic and corporate teams have responded to the agency's challenge, and friendly rivalries among teams from Stanford, Carnegie Mellon and other research hubs have led to big leaps in terrain-mapping and collision-avoidance technologies.

Lighter power packs needed

Encouraged by that success, the Defense Department now hopes to focus the same competitive drive on a threefold increase in the power-to-weight ratio of electrical storage devices that have been evolving slowly for more than 150 years.

Benjamin Franklin gets credit for coining the term "battery" during his pre-Revolutionary War experiments with kites and lightning, but it was not until the mid-1800s that batteries came to be used in telegraphs and other industrial applications of electricity.

Today, worldwide battery sales total more than $53 billion a year and grow about 7 percent annually, according to a 2005 survey by the Freedonia Group, a market research firm in Cleveland. About two-thirds of the market consists of rechargeable batteries, a category that spans the gamut from the lead-acid clunkers in cars to the lithium-ion power packs in laptops. Disposables, led by the standard alkaline battery, make up the remaining third of the market.

Today, U.S. troops are likely to go into the field packing BA-5590 lithium-ion batteries, but given the basic mandate to reduce the weight of portable power, much of the experimentation in the Wearable Power contest revolves around developing fuel cells as an alternative to batteries.

Lighter after use

Batteries and fuel cells both use chemical reactions to strip atoms of their electrons, which flow through wires as electricity. But the chemical reactions in fuel cells often are based on liquids or compressed gases that exhaust themselves as they produce electrons, venting waste gases such as carbon dioxide and water vapor. Thus, as the cell produces electricity, its fuel is gradually consumed, in contrast to batteries, which are just as heavy when they become discharged, said Jennifer Brantley, an engineer with UltraCell Corp., a Livermore firm that is competing for the Wearable Power Prize.

On a tour of UltraCell's offices, engineer Ted Prescop held up the company's XX25 fuel cell, which is roughly the size of an inch-thick hardcover book.

"It's like a little power plant," Prescop said.

UltraCell's 6-by-9-inch device is a tiny chemical processing plant in which methanol - sometimes called wood alcohol - is broken down through a series of reactions into hydrogen, the simplest element in the universe. Further chemistry lassoes hydrogen's lone electron and corrals it into producing an electrical current.

While fuel cell theory is more than a century old, in practice, the complexity of shrinking a chemical plant to book size makes fuel cells costly alternatives to batteries. The UltraCell device, for instance, lists for about $5,000, before any volume discounts. Freedonia, the market research firm that tracks battery sales, has started to monitor the fuel cell market. In 2006, it tracked just $135 million in worldwide sales, with growth projected to $670 million by 2011.

Defense officials do not expect the contest to lead to immediate cost or technology breakthroughs, nor are they wedded to fuel cells as the only way to lighten the soldier's load. But with more than 100 teams focused on the power-to-weight problem of stored electricity, they do hope to be pleasantly surprised.

"The goal of this program is not to create a field-ready system but to demonstrate and help create technologies which can then be developed into field-ready systems," said Hopkins, the Army's civilian program manager.

The competition should also stimulate the nascent fuel cell industry and other battery alternatives, as small Defense Department purchases start to create a market for these costly innovations and eventually lower prices, just as military purchases of semiconductors more than 30 years ago helped turn the transistor from a scientific oddity into the foundation of electronics.

Meanwhile, U.S. soldiers must hope the contest leads to what would be, for them, the best of both worlds - light forms of stored electricity to run their sensors and other electronics.

"Throughout the 21 years I've been in the military, we've used technology to give us the advantage," Maka said.